System and method for hierarchical paging, cell selection and cell reselection

Abstract

In one embodiment, a policy may be defined, which specifies that an operation be performed over a first set of channels before being performed over a second set of channels different than the first set of channels. The first set of channels may be associated with a first set of frequencies, and the second set of channels may be associated with a second set of frequencies. A network device may perform paging according to the defined policy. A user equipment (UE) may perform paging, page monitoring, cell selection triggered by paging, or cell reselection triggered by paging according to the policy. The policy may be hardcoded, pre-configured or dynamically configured using signaling messages.

What is claimed is: 
     
       1. A method comprising:
 obtaining, by a master node (MN) serving a user equipment (UE), a configuration specifying to page the UE in a first set of frequencies before paging the UE in a second set of frequencies higher than the first set of frequencies; 
 upon determining there is a need to page the UE, sending, by the MN according to the configuration, a paging message to the UE using a first frequency in the first set of frequencies to page the UE, the paging message comprising information of one or more secondary nodes (SNs) operable in the second set of frequencies that are to page the UE, wherein the information of the one or more SNs comprises location information of the one or more SNs, beam direction information of the one or more SNs, synchronization information of the one or more SNs for synchronizing with the one or more SNs, or paging information of the one or more SNs, the paging information of the one or more SNs further comprising a transmit receive point (TRP) ID, a scrambling code, a paging schedule, a paging resource, a beam ID or a beam direction; 
 selecting, by the MN based on location information of the UE and the information of the one or more SNs, at least one SN from the one or more SNs to page the UE; 
 instructing, by the MN after sending the paging message, the at least one SN to page the UE using the second set of frequencies; and 
 receiving, by the MN from a first secondary node of the at least one SN, a page response of the UE in response to paging the UE; and 
 wherein the method further comprises:
 determining, by the MN, the one or more SNs based on information of the UE, wherein the information of the UE comprises information of a location of the UE, a paging frame, a paging occasion, a discontinuous reception (DRX) cycle, an uplink beam direction, a resource of a random access channel (RACH), or a resource for area update (AU); and 
 
 wherein instructing, by the MN, the at least one SN to page the UE comprises:
 sending, by the MN, a SN addition request to a node of the one or more SNs, notifying that the node is added as a secondary node for paging the UE; and 
 receiving, by the MN, a SN addition acknowledgement message from the node. 
 
 
     
     
       2. The method of  claim 1 , further comprising:
 sending, by the MN, the information of the UE to the one or more SNs for paging the UE in the second set of frequencies. 
 
     
     
       3. The method of  claim 1 , further comprising:
 receiving, by the MN from the UE, a report of measurement on the one or more SNs; 
 updating, by the MN, the one or more SNs for the UEs based on the report; and 
 sending, by the MN to the UE, the updated one or more SNs. 
 
     
     
       4. The method of  claim 1 , wherein instructing, by the MN, the at least one SN to page the UE comprises:
 requesting, by the MN, a node of the one or more SNs to allocate a resource for paging the UE in the second set of frequencies. 
 
     
     
       5. The method of  claim 1 , wherein the UE is in an idle or inactive state. 
     
     
       6. The method of  claim 1 , further comprising:
 receiving, by the MN, a paging response from the UE in the first frequency. 
 
     
     
       7. A method comprising:
 obtaining, by a user equipment (UE), a configuration specifying to monitor pages in a first set of frequencies before monitoring pages in a second set of frequencies higher than the first set of frequencies; 
 monitoring, by the UE when entering a low-power mode, a first paging message in a first frequency of the first set of frequencies according to the configuration, and receiving, by the UE in the first frequency from a master node (MN), the first paging message comprising information of one or more secondary nodes (SNs) that are operable in the second set of frequencies and that are to page the UE in the second set of frequencies, wherein the one or more SNs are determined based on information of the UE, the information of the UE comprising information of a location of the UE, a paging frame, a paging occasion, a discontinuous reception (DRX) cycle, an uplink beam direction, a resource of a random access channel (RACH), or a resource for area update (AU); and 
 monitoring, by the UE after receiving the first paging message, a second paging message in the second set of frequencies according to the information of the one or more SNs, and receiving the second paging message from at least one SN of the one or more SNs, wherein the at least one SN is selected by the MN based on location information of the UE and the information of the one or more SNs, and the at least one SN is instructed to page the UE by the MN with a SN addition request and a SN addition acknowledgement message exchanged between the at least one SN and the MN; and 
 wherein the information of the one or more SNs comprises location information of the one or more SNs, beam direction information of the one or more SNs, synchronization information of the one or more SNs for synchronizing with the one or more SNs, or paging information of the one or more SNs, the paging information further comprising a transmit receive point (TRP) ID, a scrambling code, a paging schedule, a paging resource, a beam ID or a beam direction. 
 
     
     
       8. The method of  claim 7 , further comprising:
 receiving, by the UE, one or more paging messages from the one or more SNs in the second set of frequencies. 
 
     
     
       9. The method of  claim 8 , further comprising:
 sending, by the UE, a paging response to a secondary node of the one or more SNs in a second frequency of the second set of frequencies in response to receiving the one or more paging messages. 
 
     
     
       10. The method of  claim 8 , further comprising:
 sending, by the UE, a random access preamble to a secondary node of the one or more SNs in a second frequency of the second set of frequencies in response to receiving the one or more paging messages. 
 
     
     
       11. The method of  claim 8 , further comprising:
 scanning, by the UE, channels in the second set of frequencies in a cell selection or cell reselection process; and 
 selecting, by the UE, a secondary node from the one or more SNs as a serving node of the UE based on scanning the channels. 
 
     
     
       12. The method of  claim 7 , further comprising:
 sending, by the UE to the MN, the information of the UE. 
 
     
     
       13. The method of  claim 7 , wherein the UE is in an idle or inactive state. 
     
     
       14. An apparatus comprising:
 a non-transitory memory storage comprising instructions; and 
 one or more processors in communication with the memory storage, wherein the one or more processors executes the instructions to cause the apparatus to perform: 
 obtaining, by the apparatus as a master node (MN) serving a user equipment (UE), a configuration specifying to page the UE in a first set of frequencies before paging the UE in a second set of frequencies higher than the first set of frequencies; 
 upon determining there is a need to page the UE, sending, by the MN according to the configuration, a paging message to the UE using a first frequency in the first set of frequencies to page the UE according to the configuration, the paging message comprising information of one or more secondary nodes (SNs) operable in the second set of frequencies that are to page the UE, wherein the information of the one or more SNs comprises location information of the one or more SNs, beam direction information of the one or more SNs, synchronization information of the one or more SNs for synchronizing with the one or more SNs, or paging information of the one or more SNs, the paging information of the one or more SNs further comprising a transmit receive point (TRP) ID, a scrambling code, a paging schedule, a paging resource, a beam ID or a beam direction; 
 selecting, by the MN based on location information of the UE and the information of the one or more SNs, at least one SN from the one or more SNs to page the UE; 
 instructing, by the MN, the at least one SN to page the UE using the second set of frequencies; and 
 receiving, by the MN from a first secondary node of the at least one SN, a page response of the UE in response to paging the UE; and 
 wherein the one or more processors executes the instructions further to cause the apparatus to perform:
 determining, by the MN, the one or more SNs based on information of the UE, wherein the information of the UE comprises information of a location of the UE, a paging frame, a paging occasion, a discontinuous reception (DRX) cycle, an uplink beam direction, a resource of a random access channel (RACH), or a resource for area update (AU); and 
 
 wherein instructing, by the MN, the at least one SN to page the UE comprises:
 sending, by the MN, a SN addition request to a node of the one or more SNs, notifying that the node is added as a secondary node for paging the UE; and 
 receiving, by the MN, a SN addition acknowledgement message from the node.